5ktq brakes

I was road testing an 86 5ktq with 217000 kms. After a long fairly hard
braking from about 120kph to a standstill, the triangle with brake symbol
flashed a few times and a warning chime sounded. This went away after a few
seconds. I latter noticed that as the car comes to a stop, there is a sort
of kick back or"burp" felt through the pedal - as if something were
releasing. Do those puppies have a "bomb" reservoir a la BMW??
Also, it registers .2 or .3 BAR at idle; .4 or .5 at 120kph and 1.2 at full
throttle. I saw some figures recently - are these OK?